Local Time-Dependent Charging in a Perovskite Solar Cell
| Autor: | Victor W. Bergmann, Stefan A. L. Weber, Rüdiger Berger, Simon A. Bretschneider, Alexander Klasen, Yunlong Guo, Hideyuki Tanaka, Eiichi Nakamura, Ilka M. Hermes, Dan Li |
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| Rok vydání: | 2016 |
| Předmět: |
Kelvin probe force microscope
Materials science Charge density Perovskite solar cell 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Space charge 0104 chemical sciences Scanning probe microscopy Hysteresis Depletion region Chemical physics General Materials Science Atomic physics 0210 nano-technology Perovskite (structure) |
| Zdroj: | ACS Applied Materials & Interfaces. 8:19402-19409 |
| ISSN: | 1944-8252 1944-8244 |
| DOI: | 10.1021/acsami.6b04104 |
| Popis: | Efficient charge extraction within solar cells explicitly depends on the optimization of the internal interfaces. Potential barriers, unbalanced charge extraction, and interfacial trap states can prevent cells from reaching high power conversion efficiencies. In the case of perovskite solar cells, slow processes happening on time scales of seconds cause hysteresis in the current-voltage characteristics. In this work, we localized and investigated these slow processes using frequency-modulation Kelvin probe force microscopy (FM-KPFM) on cross sections of planar methylammonium lead iodide (MAPI) perovskite solar cells. FM-KPFM can map the charge density distribution and its dynamics at internal interfaces. Upon illumination, space charge layers formed at the interfaces of the selective contacts with the MAPI layer within several seconds. We observed distinct differences in the charging dynamics at the interfaces of MAPI with adjacent layers. Our results indicate that more than one process is involved in hysteresis. This finding is in agreement with recent simulation studies claiming that a combination of ion migration and interfacial trap states causes the hysteresis in perovskite solar cells. Such differences in the charging rates at different interfaces cannot be separated by conventional device measurements. |
| Databáze: | OpenAIRE |
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